/Engine/Source/Editor/LevelEditor/Public/LevelViewportTabContent.h
Starts the tab content object and creates the initial layout based on the layout string
virtual void Initialize ( AssetEditorViewportFactoryFunction Func, [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [SDockTab](API\Runtime\Slate\Widgets\Docking\SDockTab) > InParentTab, const [FString](API\Runtime\Core\Containers\FString) & InLayoutString )